1. Field of the Invention
The present invention concerns a high strength copper alloy of excellent bending processability. More specifically, it relates to a high strength copper alloy of excellent bending processability that is suitable for use in terminals, connectors, etc. used in electric and electronic equipment of air crafts and large computers, etc.
2. Description of the Prior Art
Generally, extremely high reliability is demanded for various properties of spring material for terminals, connectors, etc. used for electric and electronic equipment in aircrafts, large computers, etc. In particular, along with a recent trend of reduction in the size of electric and electronic equipment, it has been required to reduce the thickness of spring material used for such equipments. In order to compensate for the reduction in reliability caused by the reduction in the thickness, in view of the strength, more strength has now been demanded for the spring material (tensile strength of not less than 80 kgf/mm.sup.2).
It is known that beryllium-copper (Be-Cu) is a spring material having such high strength. Beryllium-copper having high tensile strength of about 100 kgf/mm.sup.2 and satisfactory bending processability is used as reliable material.
However, since beryllium and beryllium oxide are toxic to human bodies, various protection measures have to be taken when producing terminals, connectors, etc. made of beryllium-copper. Further, since beryllium is expensive, products made of beryllium-copper are also expensive. Further, the beryllium-copper involves a problem that solderability is not satisfactory.
On the other hand, high strength copper alloys which are safe and sanitary to human bodies and are comparable with beryllium-copper, C72700 Cu-9wt%Ni-6wt%Sn) and, Cu-4wt%Ti, etc. are known. All of these alloys have tensile strength of not less than 100 kgf/mm.sup.2. However, since the elongation property is lower as compared with that of beryllium-copper, cracks develop upon bending working. That is, since the bending processability is not satisfactory, they have not yet been used entirely as a substitute for beryllium-copper.